With their 66° apparent field of view, our Expanse wide-field eyepieces will definitely turn up the "Wow!" factor in your telescopic deep-sky observing sessions. Imagine taking in celestial objects like the Andromeda Galaxy, the Double Cluster of Perseus, or the star clouds in Sagittarius in one sweep - with an Expanse eyepiece in your telescope focuser, you can!

Expanse oculars have big eye lenses and great eye relief (13mm to 17mm). Eyeglass wearers can view the entire field without removing their glasses. All eyepiece elements are fully coated, with the outer lens multi-coated for additional light transmission.

You will be impressed, as we were, with the sharpness of these eyepieces as well as with the good color correction and contrast. And compared to typical Plossl eyepieces with their 52° apparent field of view, you'll quickly become spoiled by the dreamy and wide 66° window of the Expanse.

Each 1.25" aluminum eyepiece barrel is threaded for filters and internally blackened to eliminate internal light scattering. A setscrew safety recess is machined into each barrel to prevent the eyepiece from falling out should the locking setscrew inadvertently loosen up. Fold-down rubber eyeguards enhance contrast by blocking stray and peripheral light.

With our Expanse telescope eyepieces you get a super wide field of view and superior optical performance. And check out the price. You also get a bargain! Sold individually or in a money-saving set of four.

Apparent field of view

The edge-to-edge angular diameter of the image displayed in a binocular as seen by the eyes of the observer. It is an inherent specification for a given binocular design. The "angular diameter" of an object is defined as the angle an object makes (subtends) as seen by an observer.

Coatings

Binocular lenses and prisms are often coated with anti-reflective material to minimize light loss as light travels through the multiple optical surfaces of a typical binocular. Coatings help maximize the amount of light transmitted through each glass surface of a binocular, so as much light as possible reaches the observer's eyes to provide a bright and sharp image.

Good lenses are at least "fully coated," with a single layer of magnesium fluoride coating applied to each air-to-glass lens surface. Multiple layers of coatings are even more effective; the term "multi-coated" means one or more air-to-glass lens surface has multiple coatings. "Fully multi-coated" optics are even better, meaning all lens surfaces have multiple layers of anti-reflective coatings applied for maximum light transmission and optimal image quality.

Parfocal

Barrel security recess

The barrel security recess is a shallow groove or depression cut into the 1.25" or 2" barrel of the eyepiece. In the event the thumb screw holding the eyepiece in the focuser becomes slightly loose, the eyepiece will not fall out because the tip of the thumb screw will catch on the lip of the security groove.

Stratus eyepieces deliver a wide 68-degree apparent field of view which allows you to see much more than a typical 52-degree Plossl. 8-element optics yield sharp, high contrast views while generous eye relief provides a comfortable visual experience.

Stratus eyepieces deliver a wide 68-degree apparent field of view which allows you to see much more than a typical 52-degree Plossl. 8-element optics yield sharp, high contrast views while generous eye relief provides a comfortable visual experience.

A great tool for bringing out details in the planets and Moon is this 1.25" set of four Orion Color Telescope Filters. Each colored filter brings out different details in the planets allowing for a totally different view.

For deep sky observing in light-polluted areas this 1.25" Orion SkyGlow Broadband Telescope filter is perfect. It blocks the most common wavelengths of light pollution for increased contrast and better views.

The Orion UltraBlock NB Eyepiece Filter is for deep-sky observers in highly light-polluted areas. This 1.25" filter blocks all forms of light pollution allowing you to see fainter deep-sky objects than you would with wideband filters or unfiltered.

For highly light-polluted sites, the UltraBlock Narrowband Light-Pollution Filters are perfect. They block all forms of light pollution, allowing you to see fainter deep-sky celestial objects over unfiltered and wideband-filtered views.

Having trouble viewing details on the Moons surface? This neutral-density eyepiece filter reduces glare so you can see more detail and surface features. The 1.25" Orion 13% Transmission Moon Filter is especially useful with large aperture telescopes.

Would you like more contrast and less glare while viewing the moon and bright planets? The 1.25" Orion Variable Polarizing Telescope Filter reduces both and brings out details. And you can adjust the amount of light transmission for the perfect view.

For cleaning the lenses in your telescope or binocular, the Orion Microfiber Optics Cleaning Cloth lifts dirt, fingerprints, water and oil from surface without scratching, streaking or smearing delicate lens surfaces. The cloth is machine washable.

At Orion, we are committed to sharing our knowledge and passion for astronomy and astrophotography with the amateur astronomy community. Visit the Orion Community Center for in-depth information on telescopes, binoculars, and astrophotography. You can find astrophotography "how to" tips and share your best astronomy pictures here. Submit astronomy articles, events, & reviews, and even become a featured Orion customer!